1. Field of the Invention
This invention relates to an improved flexible laminate that includes multiple film layers and which is used in shipping, storage, and preservation of foodstuffs, medical supplies or like items that may be heat sensitive. The present invention also relates to flexible laminates which are used in sheet or rolled form to provide thermal, aqueous vapor, and environmental barriers in buildings or structures such as homes, factories or storage facilities. The present invention is defined as a thermal barrier with respect to the reflection and insulation from impinging thermal radiation from the ultra-violet to the long-wave infrared wavelengths emitted by any thermal source.
2. General Background of the Invention
There is a need in remote seafood processing locations, such as rural Alaska, for improved materials and methods to be used in the short-term holding and transportation of fresh fisheries products. This need stems from: the high costs associated with transporting Styrofoam-based packaging that requires a large storage volume. Also in dealing with the many unanticipated events of the fishing year and the consumer markets for the products, if the demand for Styrofoam-based products has not been accurately forecast, supplies of packaging materials may be low when the volume of fresh seafood products is high. In these circumstances of high processing volume and depleted stores of Styrofoam packaging, gel ice in Wetlock cases (wax-coated corrugated cardboard boxes) is not the preferred substitute, but it is now all that is available.
Prior use of laminates has been in electrostatic, vapor barrier or container forms which solely rely on the imperviousness and strength of the material to retain an object or material with the confines of the form. Unlike prior containers of barrier materials the present invention provides properties through a unique lay-up of materials which provide thermal, vapor and strength qualities which exceed the usual composition and fabrication.
The U.S. Patents mentioned herein are incorporated herein by reference.
A number of patents have issued for various metallized fabrics and layered film constructions that purport to provide heat retention, insulation or like qualities.
Metallized fabric is the subject of U.S. Pat. No. 4,508,776. In the '776 patent, a microporous metallized fabric suitable for use as a thermally insulating material in a hostile environment includes a microporous fabric substrate for example of a spun bonded polyethylene having a layer of aluminum deposited thereon by a vacuum depositing technique. A thin layer—typically of 0.9-1.0 g/m2-of a polyamide based ink is then printed on to the metallizing, by way of a photogravure printing process, in such a way as not to affect the porous structure of the metallized fabric. The metallized fabric of this invention finds a particular application as screening for commercial glass-houses, to reduce the heat losses therefrom.
The Workman patent, U.S. Pat. No. 4,537,313, provides an insulated bag of a multi-layer construction employing nylon fabric as inner and outer liners, thermal suede as a thermal insulation inside the outer liner, needle punched Dacron fabric as a vapor and thermal barrier, aluminum foil as a thermal barrier, and metallized Mylar as a vapor barrier.
Another metallized fabric is the subject of U.S. Pat. No. 4,657,807. In the '807 patent, a bright finish metal-covered fabric having a metal layer deposited on fabric is disclosed. A fabric, selected to be capable of flattening or polishing under heat and pressure, is pressed against a heated surface and is then vacuum metallized. In a preferred embodiment, a thermoplastic fabric is flattened against a hot roll in a calender press under high pressure, and aluminum is then vapor-deposited.
A thermal gain sensor is the subject of U.S. Pat. No. 4,401,104.
A metal foil or plastic film clad reinforced resin substrate is disclosed in U.S. Pat. No. 4,916,016.
An insulation structure for appliances is disclosed in U.S. Pat. No. 4,985,106 issued to Nelson.
A freight container insulating system and method is the subject of U.S. Pat. No. 5,105,970.
U.S. Pat. No. 5,108,821 discloses a self-extinguishing blanket enclosed with plastic films.
A leak-proof insulating system for freight containers is disclosed in U.S. Pat. No. 5,143,245. The portions of the apparatus are in the form of multi-layered side walls. Part of the construction uses cross-linked polyethylene foam.
The Anderson patent, U.S. Pat. No. 5,324,467, discloses a process for preparation of oriented multi-layer laminate film.
The present invention is an improvement over these prior art patented constructions.